Replacing the Air Mass Meter on a 940T

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tands@ukonline.co.uk - 31 Mar 2006 17:25 GMT

I'm going through, bit by bit, replacing parts in order to try to fix
whatever is causing my '93 940 turbo to threaten to stall. I only get
the problem when the engine is up to temperature (never when cold) and
it's not dropping off when cruising - it just threatens to stall if
I've slowed down and the revs drop below 2000. They just keep on
dropping.

Anyway, a couple of error codes came up when the mechanics checked, but
all of the items that could be at fault are working to spec. So the
only solution is to replace each part until I've replaced the one
that's at fault - this could get very expensive!

This weekend, I'm replacing the AMM having picked one up second hand.
Instructions for a dummy would be appreciated. Looking at it, there are
two clamp-clips connecting rather fat hoses on each side of the AMM and
an electrical connection on top. I'm assuming I just detach everything
and substitute in the replacement.

Is this some kind of pressurised section? A sealed air hose/piece that
I shouldn't play with?

Any help or advice gratefully received.

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Beck - 31 Mar 2006 19:16 GMT

> I'm going through, bit by bit, replacing parts in order to try to fix
> whatever is causing my '93 940 turbo to threaten to stall. I only get
[quoted text clipped - 18 lines]
>
> Any help or advice gratefully received.

I can't help you with the AMM but we have just gone through the same process
with our 240e. Not the same model but similar symptoms - stalling when
slowing down and when the engine is warm. After many part swaps it turned
out to be the Fuel Pump Relay. Worth a look maybe?

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tands@ukonline.co.uk - 31 Mar 2006 19:40 GMT

> I can't help you with the AMM but we have just gone through the same process
> with our 240e. Not the same model but similar symptoms - stalling when
> slowing down and when the engine is warm. After many part swaps it turned
> out to be the Fuel Pump Relay. Worth a look maybe?

Thanks for the shout. I read a few people mentioning the fuel pump
relay. It's one of the lists of bits that could be at fault. Being a
very simple and cheap replacement, I'd hoped it would be. Alas, I
changed it last weekend, but to no avail.

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Beck - 31 Mar 2006 19:47 GMT

>> I can't help you with the AMM but we have just gone through the same
>> process with our 240e. Not the same model but similar symptoms -
[quoted text clipped - 6 lines]
> very simple and cheap replacement, I'd hoped it would be. Alas, I
> changed it last weekend, but to no avail.

Also check the Throttle body which we did. Should not need replacing but
could probably do with a good clean inside as gunk builds up in it and can
cause similar problems. On our car it was attached next to the air mass
meter so you should be able to find it easily.
As for removing the AMM, just having a quick think back, I think all my Dad
did to remove the AMM was to unclip it and remove the electrical connection
then replace it. Not too big a job, just awkward as the clamp screws were
in a hard to reach place.

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Beck - 31 Mar 2006 19:50 GMT

Just asked my Dad for the right info, if its the same connection type
(although not the same model) just undo the jubilee clips and unscrew the
bolt and it should come off cleanly.

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zencraps@comcast.net - 02 Apr 2006 19:35 GMT

I just replaced the AMM in an '85 245 and will advise you as follows:
test it, or have it tested with a VOM (volt-ohm-meter) before
installing it.

The test is very easy and quick, you just touch the electrical leads to
certain spots and look at the readings.

If the AMM is good, it will read within certain specifications; if it
is out of spec, it is defective.

I had to check a couple used AMMs before I found one that wasn't bad.

Sounds like you're a newbie and haven't a clue what a VOM is or how to
use it; if so, take the used VOM to a Volvo repair shop and ask them to
test it.

The last thing you want to do is put in a bad AMM, thinking it is good,
have the problem remain uncorrected, and keep trying to troubleshoot.

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